Comparative study on the illumination model of fishing lamps based on point light sources and spherical light sources

Illumination estimation is an important research content in mixed reality technology. This paper presents a novel method for locating multiple point light sources and estimating their intensities from the images of a pair of reference spheres. In our approach, no prior knowledge of the location of the sphere is necessary, and the center of the sphere can be uniquely identified with the known radius. The sphere surface is assumed to have both Lambertian and specular properties instead of being a pure Lambertian or specular surface, which guarantees a higher accuracy than the existing approaches. The position estimations of multiple light sources are based on the fact that the specular reflection is highly dependent on highlights. One sphere is utilized to determine the directions of the light sources, and two spheres are used to locate the positions. The images of reference spheres are sampled and partitioned with multiple light sources in different positions. An illumination model is used to calculate the intensities of the ambient light and multiple light sources. Experiments on both simulation and synthetic images show that this method is feasible and accurate for estimating the positions and intensities of the multiple light sources.

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Dimension Measurement of Objects With Circular Cross Section Using Point Light Sources and an Image Sensor Without Lens

IEEE Transactions on Instrumentation and Measurement ◽

10.1109/tim.2007.900130 ◽

2007 ◽

Vol 56 (4) ◽

pp. 1403-1411 ◽

Cited By ~ 1

Author(s):

Tom Radil ◽

Jan Fischer ◽

Jan Kucera

Keyword(s):

Cross Section ◽

Circular Cross Section ◽

Image Sensor ◽

Light Sources ◽

Dimension Measurement ◽

Point Light

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A Practical Method for Estimation of Point Light-Sources

Procedings of the British Machine Vision Conference 2001 ◽

10.5244/c.15.49 ◽

2001 ◽

Cited By ~ 13

Author(s):

M Weber ◽

R Cipolla

Keyword(s):

Practical Method ◽

Light Sources ◽

Point Light

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Ray Tracing Based on Interpolation of Visibility of Point Light Sources

Studies in Computational Intelligence - Intelligent Computer Graphics 2012 ◽

10.1007/978-3-642-31745-3_9 ◽

2013 ◽

pp. 169-188

Author(s):

Victor A. Debelov ◽

Iliya Novikov ◽

Lyudmila Vasilyeva

Keyword(s):

Ray Tracing ◽

Light Sources ◽

Point Light

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Optical Losses in Hybrid Microcavity Based in Porous Semiconductors and its Application as Optic Chemical Sensor

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.56.158 ◽

2019 ◽

Vol 56 ◽

pp. 158-167

Author(s):

Claudia Antonio Hernández ◽

Edith Osorio ◽

Raúl Urteaga ◽

Roberto Koropecki ◽

José Alberto Alvarado ◽

...

Keyword(s):

Chemical Sensor ◽

Visible Region ◽

Bragg Reflector ◽

Resonant Peak ◽

Light Sources ◽

Optical Losses ◽

Distributed Bragg Reflector ◽

Nanoporous Anodic Alumina ◽

Porous Semiconductors ◽

Point Light

In this study the experimental and theoretical optical analysis of a hybrid microcavity (HM) based in porous silicon (PS) and nanoporous anodic alumina (NAA) are presented. The microcavity was centered in the visible region at 760 nm. Distributed Bragg reflector (DBR) was obtained using galvanostatic anodizing method and while NAA by the two-step anodization technique. From SEM micrographs the HM different regions are observed. HM optical characterization in the visible region was done, considering two different light sources, point and non-point respectively. These results reveal a decrease in the quality factor (Q) from 350 to 190 when the source is exchanged; this behavior has been mainly attributed to the light scattering at NAA. Furthermore, it was possible to study Q change, through transmittance simulation using the transfer matrix and Landau-Lifshitz-Looyenga theoretical methods. When a point light source is used, there are no optical losses making possible to sense 1% of analyte resulting in a 0.29 nm redshift of the resonant peak. According with these results we propose to apply the HM as chemical optic sensor.

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Shape from shading using near point light sources

Lecture Notes in Computer Science - Image Analysis Applications and Computer Graphics ◽

10.1007/3-540-60697-1_138 ◽

1995 ◽

pp. 487-488 ◽

Cited By ~ 1

Author(s):

Sheng-Liang Kao ◽

Chiou-Shann Fuh

Keyword(s):

Shape From Shading ◽

Light Sources ◽

Point Light

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Photocatalytic degradation of the dye sulforhodamine-B: A comparative study of different light sources

Journal of Environmental Sciences ◽

10.1016/s1001-0742(07)60016-3 ◽

2007 ◽

Vol 19 (1) ◽

pp. 97-102 ◽

Cited By ~ 21

Author(s):

Yan-fen FANG ◽

Ying-ping HUANG ◽

De-fu LIU ◽

Yang HUANG ◽

Wei GUO ◽

...

Keyword(s):

Comparative Study ◽

Photocatalytic Degradation ◽

Light Sources ◽

Sulforhodamine B

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Mitigation of even harmonics in the Fourier components of vertical illuminance around a reference point

Lighting Research and Technology ◽

10.1177/1477153519880584 ◽

2019 ◽

Vol 52 (5) ◽

pp. 675-691

Author(s):

RA Mangkuto ◽

B Paramita ◽

SS Utami

Keyword(s):

Sensitivity Analysis ◽

Reference Point ◽

Point Sources ◽

Light Sources ◽

Sensitivity Analysis Method ◽

Genetic Algorithm Method ◽

Components Analysis ◽

Optimisation Methods ◽

Point Light ◽

Even Harmonics

The use of Fourier components analysis has been recently proposed by Lynes to describe harmonics in vertical illuminance at various azimuth angles around a reference point. In cases with multiple light sources, it has been argued that the removal of even harmonics in the resulting Fourier components may correspond with good lighting practice. This paper therefore aims to demonstrate optimisation methods to mitigate even harmonics in Fourier components of vertical illuminance around a reference point due to two and three point light sources, by adjusting maximum vertical illuminance and subtended angles between the sources using sensitivity analysis and genetic algorithms. The results suggest that the genetic algorithm method yields more precise optimum solutions compared with the sensitivity analysis method, particularly for scenes with three point sources. For two point sources, the smallest root mean square value of even harmonics is achieved when the vertical illuminance due to the second source is 0.92 (relative to the vertical illuminance due to the first source) and the subtended angle is 90°. For three point sources, the optimum vertical illuminance due to the second and third sources is respectively 0.81 and 0.78, whereas the optimum subtended angles for the second and third sources with respect to the first are 64.4° and 116.8°, respectively.

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